Natural Stable Isotopes for Determination of Gastrointestinal Transit Time in Fish

This study evaluated the application of stable isotopes of carbon as an alternative and more accurate method to determine gastrointestinal transit time (GTT) in fish by comparing it to the inert marker method. The stable isotope method detects alterations of the normal carbon flow in a biological system by analyzing naturally occurring isotopes of carbon, contrary to studies based on conventional techniques that apply external markers to the diet to determine GTT through visual observation of the color change in feces. Therefore, 320 pacu, Piaractus mesopotamicus juveniles were reared in 32 tanks under two different temperatures (25 and 29 C). The pacu juveniles received two different diets, one based on ingredients derived from C₃ photosynthetic cycle plants and the other based on C₄ plant ingredients, both containing titanium oxide (TiO₂) as a marker. After 40 d, the isotopic signature of the diets was changed, and the marker was replaced by chromic oxide (Cr₂O₃). In the isotopic technique, the feces were analyzed to determine the exchange in the isotopic ratio of carbon δ¹³C. Both methods found that GTT was faster (nearly 6 h) in fish at 29 C when using the C₄/C₃ feeding strategy and slower in fish at 25 C using the C₃/C₄ strategy (15 h by inert marker and 18 h by the isotopic method). In conclusion, GTT determination in pacu juveniles using the stable isotope technique exhibits the same accuracy obtained with the inert marker method at temperatures suitable (nearly 29 C) for the metabolism of these animals.     

Does reverse growth dominance develop in old plantations of Eucalyptus saligna?

Patterns of stand growth and dominance among individual trees change through stand development. We tested a prediction that large, old plantations of Eucalyptus saligna (Sm.) in Hawaii and Brazil would show a pattern of “reverse” growth dominance, with the largest trees contributing more to stand biomass than to current stand increment. This pattern might develop if the largest trees accounted for a large portion of the total resource use of the stand, but were less efficient at utilizing resources to produce stemwood. The 70-year-old plantation in Hawaii had a stem mass of 610 Mg/ha, compared with 325 Mg/ha in the 66-year-old Brazil plantation. Cumulative frequency plots for both sites showed that dominant trees comprised a very large proportion of total stand mass; the largest 20% of the trees accounted for 50% and 30% of the total stand mass in Hawaii and Brazil, respectively. Contrary to expectations, the largest trees continued to produce a disproportionately large amount of total stand growth, with the largest 20% of trees accounting for 60% (Hawaii) and 40% (Brazil) of stand growth. The frequency distributions resulted in positive growth dominance coefficients (similar to Gini coefficients) of 0.14 for Hawaii and 0.09 for Brazil, rather than negative values that would indicate that reverse growth dominance. The failure of these monoculture Eucalyptus stands to develop reverse growth dominance contrasts starkly with a variety of studies with pine species, which tend to show neutral-to-reverse growth dominance. Indeed, continued dominance of large trees suggests the trees might respond well to silvicultural treatments such as thinning or fertilization. Future work that contrasts patterns of growth dominance among species will be important as a foundation for developing generalizations about trends in growth dominance with stand development.     

New mite-borne virus isolates from rakkyo,shallot and wild leek species

Flexuous viruses were transmitted from rakkyo (Allium chinense) and wild leek species (especiallyA. commutatum) to plants of crow garlic (A. vineale), by transfer of dry bulb mites. By electron microscope decoration tests using three antisera and by inoculations onto test plants, it was concluded that from each of the two natural host species at least two viruses were isolated. The viruses from wild leeks are both pathogenic onAllium spp. and may be of economic importance. Decoration tests on a virus mixture from shallot obtained earlier, revealed another new mite-borne virus in this species. The mite-borne viruses ofAllium spp. appear to be very common; they are largely diverse and their identification remains difficult.     

Crude protein fractions in common vetch (Vicia sativa L.) fresh forage during pod filling

Crude protein (CP) of forages can be separated into fractions of differentiated abilities to provide available amino acids in the lower gut of ruminants. This knowledge is critical to develop feeding systems and to predict animal responses. We have measured during two growing seasons (1996 to 1997 and 1997 to 1998) the CP fractions of common vetch fresh forage with the objective being to assess the influence of maturity on concentration of CP fractions (as a percentage of total CP) and fraction yields. Fraction B2, which represents true protein of intermediate ruminal degradation rate, was the largest single fraction in common vetch forage (about 40% of CP across seasons and maturity stages). Soluble fractions (A plus B1) were less than 50% of total CP while the unavailable fraction C ranged from 4 to 8% of total CP. As a result, the remaining fraction B3 (true protein of very low degradation rate) only represented 2 to 9% of total CP. Concentration and yield of fraction B3 increased (P < 0.05) from flowering to pod-filling. Results showed that undegraded dietary protein represented a small proportion of total CP in common vetch forage. Moving the harvesting stage from flowering to the pod filling phase allowed for greater yield of undegraded dietary protein.     

Disease and mortality on red deer farms in New Zealand

A longitudinal observational study of 15 red deer farms was carried out in New Zealand for two years from March 1992. The deer were monitored for performance and health problems, and farm management practices were recorded. Numbers at risk were 4,683 hind-years, 2,459 stag-years and 3,202 weaner-years. The numbers of primiparous and adult hinds at risk of losing their progeny by weaning were 653 and 3,364, respectively. Where possible, postmortem examinations were carried out, and organs were sampled for histological and microbiological investigation. Rates of mortality varied with season with most stag and hind deaths in winter and weaner deaths in autumn and winter. Overall mortality rates were 1.77, 2.60 and 5.87 per 100 deer-years for hinds, stags and weaners, respectively. Malignant catarrhal fever accounted for 0.53 stag and 0.17 hind deaths per 100 deer-years at risk Misadventure, including broken bones, accounted for 15.4 per cent of weaner mortalities, or 0.53 weaner mortalities per 100 weaner-three months in autumn. Yersiniosis was confirmed in 18.6 per cent of weaner deaths, or 1.09 weaners per 100 weaner-years during the first six months after weaning, but was also suspected but unconfirmed in a further 41 per cent of weaner mortalities. Overall, 17 per cent of yearling hinds, and 9.2 per cent of adult hinds lost their progeny between pregnancy diagnosis in June and weaning in March. One outbreak of osteochondrosis was recorded. Mortality rates varied between farms and many mortalities were preventable.     

Open reduction of sacral fractures using transarticular implants at the articular facets of L7-S1: 8 consecutive canine patients (1995-1999)

OBJECTIVE: To describe and evaluate facet stabilization as an aid for open reduction and fixation of sacral fractures. STUDY DESIGN: A clinical case series. STUDY POPULATION: Eight consecutive client-owned dogs with sacral fractures. METHODS: A combination of a standard lateral approach to the ilium and a dorsal approach to the articular facets of L7-S1 was performed. The articular facets were reduced and stabilized with a Kirschner wire or a combination of a Kirschner wire and a cortical screw. Primary stabilization of the sacrum was then accomplished using a cortical screw inserted from the lateral aspect of the ilium, through the sacral fracture into the body of the sacrum. Accuracy of reduction, position of the implants, percent screw depth/sacral width, pelvic canal diameter ratio, and complications were assessed using radiographs and physical examination. RESULTS: Mean sacral fracture reduction was 91% immediately after surgery, and was 87% when measured at follow-up examinations. Mean screw depth/sacral width was 66%. Mean pelvic canal diameter ratio was 1.12 postoperatively and 1.03 at the 4- to 6-week reevaluation. Six of the 8 dogs were using the leg well 10 to 12 days after surgery; none had clinically detectable neurologic deficits. The long-term (mean, 2.7 years) outcome for these dogs was good (normal to grade I lameness). CONCLUSION: Fixation of the L7-S1 facet joints facilitates repair of sacral fractures.     

Alteration of body composition in rats: effect of organic chromium and L-carnitine

A growth trial was carried out to test the effect of organic, trivalent chromium and L-carnitine on the body composition of growing rats. At the same time, an evaluation of different measurement methods (weight of epididymal fat pad, adipocyte morphometry, total body electrical conductivity) was performed. Outbred Wistar rats of 30 days of age were fed diets of different (0, 10 and 20%) protein level. The diets were supplemented with 4 mg/kg Cr as chromium nicotinate, and 100 mg/kg L-carnitine. The experimental feeding lasted 15 days, after a 5-day-long adjustment period. It was found that Cr addition increased feed intake. Both treatments caused changes in body composition, increasing fat and protein deposition. Organic chromium had no effect at either protein level, while L-carnitine improved the protein retention only at an optimum (20%) protein supply. No statistically significant correlation was found between total body electrical conductivity (TOBEC) and body composition, which could be attributed to the great individual differences. A close correlation was found among total body fat percentage, weight of epididymal fat pad and the adipocyte surface. The data suggest that there is an interaction between dietary protein supply and the effect of repartitioning agents.     

Influence of feeding intensity on corporeal development, body composition and sexual maturity in female rabbits

Twenty-six 6-week old female New Zealand White rabbits were divided into two groups: ad libitum (AL) and 70% restricted (RS) feeding. At the beginning of the experiment the liveweights were practically the same: 0.99 +/- 0.08 vs. 1.01 +/- 0.08 kg in group AL and RS, respectively. At 18 weeks of age the body weight of Group RS rabbits was 84.7% (3.14 +/- 0.24 kg) of the group AL (3.71 +/- 0.31 kg). The apparent digestibility of crude protein was significantly (p < 0.001) higher in Group RS than in Group AL (76.5 +/- 1.4 vs. 73.0 +/- 2.7%). The daily water consumption was significantly (p < 0.05) higher (3.5 ml/g DM intake) in Group RS as compared to Group AL (1.9 ml/g DM). Since the average body weight in Group RS at 18 weeks was the same as that of Group AL at 14 weeks of age (3.14 kg), the comparison of the live body measures and indices was based on these ages. Animals fed ad libitum or restricted show no differences at the defined age in most live body measurements except in heart girth and rump width, which were significantly (p < 0.05) shorter in Group AL than in Group RS (29.3 +/- 0.8, 5.7 +/- 0.5 and 30.7 +/- 1.0, 6.2 +/- 0.3 cm, respectively). Body capacity was significantly (p < 0.05) smaller in Group AL, as the head capacity-body capacity proportion was significantly (p < 0.05) higher in Group AL than in Group RS (1653.1 +/- 134.5, 22.0 +/- 2.5 and 1913.7 +/- 168.7, 17.7 +/- 1.9, respectively). Due to restricted feeding the growth of the head proved to be less intensive than that of the body at the same body weight. The body in these does tended to be wider. Since the head in comparison to length or capacity of the body was smaller in does fed 70% of ad libitum, it could be concluded that the development of body parts of restricted-fed does was unequal (allometric growth). The effect of feed restriction reflected in lower dry matter and fat, and a higher ash and protein content both in total body and in dry matter composition of rabbits at 18 weeks of age. Restricted feeding delayed sexual maturity (69 vs. 92% of rabbits) with later starting ovarian activity, weaker ovarian responsiveness, and a smaller number of tertiary follicles on the ovarian surface.     

Validation of a polymerase chain reaction assay for monitoring the therapeutic efficacy of diminazene aceturate in trypanosome-infected sheep

The diagnostic performance of a polymerase chain reaction assay (PCR) for monitoring the effectiveness of aceturate diminazene treatment was compared with those of an antibody-detection ELISA test and the buffy-coat technique using sheep experimentally infected with either savannah-type or forest-type Trypanosoma congolense or T. vivax. Within the period of infection, the PCR using specific savannah-type T. congolense primers showed a significant higher diagnostic sensitivity (p<0.05) than the buffy-coat technique. Both techniques gave closed results for detecting forest-type T. congolense or T. vivax infections. Following trypanocidal treatment, the PCR showed that specific product disappeared definitively 1 or 2 days later in animals in which a decrease of the antibody level and a significant improvement of the red packed cell volume were observed. The occurrence of relapse infection was detected by the PCR in one animal infected by T. vivax on day 19 post-treatment and confirmed by the persistence and increasing antibody level whereas the buffy-coat technique detected parasites 42 days later. Then, the PCR signals remained positive on several occasions while parasitaemia was detected only two times.The application of PCR combined with the antibody detection appeared to provide a useful tool as compared to the buffy-coat technique for monitoring the effectiveness of trypanocidal treatment.     

Failure of dogs to shed oocysts after being fed bovine fetuses naturally infected by Neospora caninum

Neospora caninum is a protozoan that causes abortion in cattle. The dog has recently been identified as a definitive host for N. caninum. To verify if bovine fetuses can infect dogs, nine 2-4-month-old dogs were fed bovine fetuses naturally infected by N. caninum. None of the dogs excreted oocysts, seroconverted, had clinical signs or lesions compatible with N. caninum infection. Additional studies will be necessary to determine the natural mode of infection of dogs by N. caninum.